Different methods to provide polymers with flame resistance are known in the art: said methods are generally based on the addition to the polymer of thermolabile halogenated compounds associated with metallic compounds, specially antimonic and/or bismuthic compounds.
The combinations between metallic compound and halogenated compound generally give satisfactory results as far as the polymers characteristics of flame resistance are concerned, but they involve more or less serious inconveniences and in particular:
corrosion phenomena in the equipments wherein the treatment of polymers with such additives is carried out; PA1 worsening in the emission of darkening smokes during combustion and/or decomposition of said polymers; PA1 need of manipulating highly toxic substances such as, for example, antimony sequioxide.
It is known as well that ammonium salts of hydric acids generally have an effective action as flame retarders in many fields such as the field of paints and coatings in general, but they cannot be used directly as additives in thermoplastic polymers due to their high corrosivity with respect to metals, their extreme sensitivity to water and air humidity, and their poor thermal and thermo-oxidative stability.